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FLOOD RISK & DRAINAGE IMPACT ASSESSMENT REPORT
Higher College Farm, Hothersall, Preston
Report Ref BEK-17303-1-RevB November 2018
REPORT PREPARED FOR
MR M HURST Higher College Farmhouse
Lower Road Hothersall
Preston PR3 2YY
Project Quality Assurance Information Sheet
FLOOD RISK AND DRAINAGE IMPACT ASSESSMENT
Higher College Farm, Hothersall, Preston
Report Status Final
Report No BEK-17303-1
Rev No B
Date November 2018
Prepared For
MR M HURST Higher College Farmhouse
Lower Road Hothersall Preston, PR3 2YY
Prepared By
BEK ENVIRO LIMITED Suite One
No 3 Mitton Road Business Park Mitton Road
Whalley Lancashire
BB7 9YE
Author
David Emmott BSc (Hons) MSc AMIEnvSci
Checked By
Michael Buckley BSc (Hons) MSc MIEnvSci CEnv
Contact [email protected] www.bekenviro.co.uk
Office: 01254 377622 Mobile: 07906 753583 BEK Enviro Limited (BEK) has prepared this report for the sole use of the client, showing reasonable skill and care, for the intended purposes as stated in the agreement under which this work was completed. The report may not be relied upon by any other party without the express agreement of the client and BEK. No other warranty, expressed or implied, is made as to the professional advice included in this report. Where any data supplied by the client or from other sources have been used, it has been assumed that the information is correct. No responsibility can be accepted by BEK for inaccuracies in the data supplied by any other party. The conclusions and recommendations in this report are based on the assumption that all relevant information has been supplied by those bodies from whom it was requested. No part of this report may be copied or duplicated without the express permission of BEK and the party for whom it was prepared. Where field investigations have been carried out, these have been restricted to a level of detail required to achieve the stated objectives of the work.
Flood Risk and Drainage Impact Assessment Higher College Farm, Hothersall Report Ref BEK-17303-1- RevB November 2018
TABLE OF CONTENTS
1. INTRODUCTION 1.1 Appointment
1.2 Background
1.3 Objective
1.4 Scope of Report
1.5 Limitations
2. DESKTOP STUDY 2.1 Site Location & Layout Plan
2.2 Topographical Survey
2.3 Existing Surface Water Flow Routes, Drains, Sewers and Watercourses
2.4 Flood Risk From Main Rivers
2.5 Surface Water and Groundwater Flood Risk
2.6 Geology and Soil Type
3. FLOOD RISK ASSESSMENT
3.1 Sequential and Exception Test
3.2 Historical Flooding
3.3 Surface Water Runoff
3.4 Fluvial Flooding
3.5 Reservoir Flooding
3.6 Groundwater
3.7 Surface Water
4. INDICATIVE DRAINAGE STRATEGY
4.1 Surface Water Drainage Hierarchy
4.2 Infiltration
4.3 Discharge to Watercourse
4.4 Preliminary Drainage Design
4.5 Outfall Locations
4.6 Discharge Rates
4.7 On-Site Storage Requirements
5. CONCLUSIONS & RECOMMENDATIONS
APPENDICES Appendix A Topographical Survey
Appendix B Greenfield Runoff Rates
Appendix C On-Site Storage Requirements
Appendix D Preliminary Drainage Design
Appendix E Drawings
Flood Risk and Drainage Impact Assessment Higher College Farm, Hothersall Report Ref BEK-17303-1- RevB November 2018
DRAWINGS BEK Drawing No 17303-1 Site Location Plan
BEK Drawing No 17303-2 Site Layout Plan
Flood Risk & Drainage Impact Assessment – Higher College Farm, Hothersall Report Ref BEK-17203-1 RevB November 2018
1. INTRODUCTION
1.1 Appointment
1.1.1 BEK Enviro Limited (BEK) has been commissioned by Mark Hurst to provide a Flood Risk & Drainage Impact Assessment for Higher College Farmhouse, Hothersall, Preston (hereafter referred to as ‘the site’) to assess the potential risks associated with flood risk to the site for residential use.
1.1.2 The site is located within Flood Zone 1 of the Environment Agency Flood Map;
and as such has a low risk of fluvial flooding.
1.2 Background
1.2.1 A site specific flood risk assessment provides an appraisal of flood risk both within the application site and any potential impact that the development will have on flood risk elsewhere; and provide recommendations for mitigation measures which may be included within the design of the development to reduce the overall risk of flooding.
1.2.2 An initial assessment indicates that the primary source of flooding risk to the
development is an increase in surface water runoff as a result of development. 1.3 Objective and Scope of Work 1.3.1 The objective of this report is to evaluate the issues in regard to flood risk at the
application site i.e. development of 21 new residential units at Higher College Farm, Hothersall, Preston, Lancashire.
1.3.2 The Flood Risk and Drainage Impact Assessment has been prepared to inform ‘An
outline planning application for a self-build residential scheme’. Specifically the following information is required as a minimum:
Detailed site location and layout plans Desktop study to incorporate maps showing:
Topography of the development site, with contours at 1 m intervals
Existing surface water flow routes, drains, sewers and watercourses
Flood risk from main river and coastal sources
Surface water and groundwater flood risk
Geological and soil types
Flood Risk Assessment:
Suitability of the proposed development in accordance with current planning policy
Identify the risk to both the development and people from all forms of flooding
Provide a preliminary assessment of foul and surface water management
Flood Risk & Drainage Impact Assessment – Higher College Farm, Hothersall Report Ref BEK-17203-1 RevB November 2018
Review the relevant background information for the site, including: o National Planning Policy Framework o Planning Practice Guidance o Building Regulations Approved Document H o Environment Agency Flood Mapping o Lancashire County Council Strategic Flood Risk Assessment (2007) o BGS – Historic Borehole Logs o Cranfield University Soilscape Viewer
Recommendation of appropriate measures to mitigate against flooding both within the proposed development, and neighbouring land and property.
Indicative Site Drainage Strategy, including:
Preliminary sustainable drainage proposals
Outfall Locations
Discharge Rates
On-site storage requirements
1.4 Scope of Report 1.4.1 The information provided within this report was undertaken via a desktop
investigation using the guidance provided by Lancashire County Council in their Pre-Application Advice.
1.4.2 This report provides details of the information requested by Lancashire County
Council to demonstrate how surface water will be managed on site, satisfying the principles of Paragraph 103 of the NPPF and Paragraph 80 of Section 10 of the PPG (Planning Policy Guidance).
1.5 Limitations 1.5.1 The conclusions and recommendations presented in this report are the result of
our professional interpretation of the information currently available. BEK reserve the right to amend the conclusions and recommendations if further information becomes available.
1.5.2 However, it should be noted that much of the information has been derived from
various internet resources and BEK takes no responsibility for the accuracy of that information.
1.5.3 The comments given in this report and the opinions expressed are based on
review of information obtained by BEK.
Flood Risk & Drainage Impact Assessment – Higher College Farm, Hothersall Report Ref BEK-17203-1 RevB November 2018
2. DESKTOP STUDY 2.0.1 This section provides an overview of the information to satisfy the requirements
of Lancashire County Council in their role as Lead Local Flood Authority (LLFA). 2.1 Site Location and Layout Plan 2.1.1 The site occupies a roughly rectangular plot of agricultural land of some 1.5
Hectares (11,000 m2). The site generally falls towards the south and is currently comprised of a large agricultural field. Higher College Farmhouse and associated farm buildings are located towards the south of the site.
2.1.2 Detailed site location and layout plans are provided within Appendix E of this
report. 2.2 Topographical Survey 2.2.1 A topographical survey of the site was completed by TriCAD Solutions Ltd in May
2017 and is provided within Appendix A of this report. The site is shown to fall from north to south with the general site level shown to be around 110 mAOD.
2.2.2 The highest spot level on the topographical survey is in the north-east of the site
and is shown to be 112.23 mAOD with the lowest spot level in the south-west of the site with an elevation of 106.60 mAOD.
2.3 Existing Surface Water Flow Routes, Drains, Sewers and Watercourses 2.3.1 The existing development site is comprised of an agricultural greenfield. The
agricultural field is not anticipated to have any formal drains or sewers. There is a small existing watercourse located approximately 20 m south-west of the development site.
2.3.2 It is considered that the existing farmhouse immediately south of the site is
positively drained with surface water likely to drain towards an unnamed land drain located to the south-west of the site and foul from the existing farmhouse is likely to discharge into a septic tank.
2.3.3 There a number of manholes, inspection chambers and gullies located close to
the existing farmhouse building with surface water directed towards the lowest part of the site in the south-west.
2.3.4 A surface water flow route is located towards the west of the site which flows
from adjacent to the west of Spade Mill Reservoir No 2 in a southerly direction beneath Blackburn Road and adjacent to the west of the development site. It is understood the land drain is culverted as it flows along the western boundary of the site before becoming an open channel approximately 30 m south-west of the site.
Flood Risk & Drainage Impact Assessment – Higher College Farm, Hothersall Report Ref BEK-17203-1 RevB November 2018
2.4 Flood Risk from Main Rivers 2.4.1 The Environment Agency flood map indicates that the development site is
located wholly within Flood Zone 1 as shown within the Figure overleaf. Flood Zone 1 is defined as land with a low probability (less than 1 in 1000 year (<0.1% AEP) annual probability of river or sea flooding in any year.
2.4.2 As such the risk of Main River and coastal flooding to the development site is
considered to be low.
Figure 1: Environment Agency Flood Map Key
2.5 Surface Water and Groundwater Flood Risk 2.5.1 Figure 2 below indicates that the risk of flooding from surface water to the
development site is very low to low. 2.5.2 However there is a surface water flow route which flows in a southerly direction
to the west of the site. The depth of flooding from this surface water flow route during the low risk event is below 300 mm adjacent to the development site.
Development Site
Flood Risk & Drainage Impact Assessment – Higher College Farm, Hothersall Report Ref BEK-17203-1 RevB November 2018
Figure 2 : Environment Agency Flood Risk from Surface Water Map Key
High Medium Low Very Low
2.5.3 The risk of groundwater flooding to the site is considered to be low with the
Environment Agency Groundwater Designation Map indicating that the site is underlain by superficial deposits classified as a ‘Secondary Undifferentiated Aquifer’.
2.5.4 The Environment Agency describes Secondary undifferentiated aquifers as: ‘Undifferentiated aquifers has been assigned where it has not been possible to
attribute either category A or B to a rock type. In most cases, this means that the layer in question has previously been designated as both minor and non-aquifer in different locations due to the variable characteristics of the rock type’
Development Site
Flood Risk & Drainage Impact Assessment – Higher College Farm, Hothersall Report Ref BEK-17203-1 RevB November 2018
Figure 3: Environment Agency Groundwater (Superficial Deposits)
Key
2.5.5 The bedrock aquifer designation is shown within the Figure below with the site shown to be located on bedrock classified as a ’Secondary A Aquifer’ described as:
‘permeable layers capable of supporting water supplies at a local rather than
strategic scale, and in some cases forming an important source of base flow to rivers. These are generally aquifers formerly classified as minor aquifers’
Site
Flood Risk & Drainage Impact Assessment – Higher College Farm, Hothersall Report Ref BEK-17203-1 RevB November 2018
Figure 4: Environment Agency Groundwater (Bedrock Deposits)
Key
2.5.6 Due to the location of the site on an undifferentiated secondary superficial
aquifer with a bedrock designation as a Secondary A aquifer it is not considered likely that groundwater flooding would pose a significant risk to the proposed site. Furthermore the Ribble Valley Strategic Flood Risk Assessment states that:
‘Groundwater flooding is not considered by the Environment Agency to be a
significant flood risk factor in the Ribble Valley Borough Council area.’ 2.6 Geology and Soil Type 2.6.1 Information from the British Geological Society indicates that the bedrock
geology at the development site is comprised of the Warley Wise Grit Member consisting of sandstones with part of the north of the site shown to be the Pendle Grit Member consisting of sandstone and siltstone.
Site
Flood Risk & Drainage Impact Assessment – Higher College Farm, Hothersall Report Ref BEK-17203-1 RevB November 2018
Figure 5: BGS Bedrock Deposits
2.6.2 The superficial geology is Till, Devensian – Diamicton (Boulder Clay). The soil type
beneath the development site is considered to be slowly permeable seasonally wet acid loamy and clayey soils with impeded drainage.
Figure 6: Soilscapes Viewer
Key
Site
Site
Flood Risk & Drainage Impact Assessment – Higher College Farm, Hothersall Report Ref BEK-17203-1 RevB November 2018
3. FLOOD RISK ASSESSMENT
3.0.1 It is usual for the Environment Agency to raise an objection to development applications within the floodplain, or Zones 2 and 3 of the Environment Agency flood map until the issue of flood risk has been properly evaluated. The Agency will also object to developments where the total site area is in excess of 1 Hectare until suitable consideration has been given to surface water runoff.
3.0.2 The proposed development site is located wholly within Flood Zone 1 however it
is greater than 1 hectare in size as such it is considered that a Site Specific Flood Risk Assessment is required.
3.1 Sequential and Exception Test 3.1.1 The objective of the Sequential Test is to steer new development to areas of the
lowest probability of flooding, this takes into account the flood zones and the flood risk vulnerability classification of developments.
3.1.2 The Environment Agency flood map indicates that the proposed development
site is within Flood Zone 1. Flood Zone 1 is defined as land assessed as having a less than 1 in 1000 annual probability of river flooding in any one year.
3.1.3 Proposals for the application site are for the development of new residential units
at the site. 3.1.4 In accordance with Table 2 ‘Flood Risk Vulnerability Classification’ of the
Technical Guidance to the National Planning Policy Framework, commercial developments are defined as ‘more vulnerable’ development.
Flood Risk Vulnerability Classification
Essential Infrastructure
Water Compatible
Highly Vulnerable
More Vulnerable
Less Vulnerable
Flood Zone
Zone 1
Zone 2
Exception
Test Required
Zone 3a
Exception Test Required
x Exception
Test Required
Zone 3b
Exception Test Required
x x x
Table 1: Flood Risk Vulnerability and Flood Zone Compatibility
Flood Risk & Drainage Impact Assessment – Higher College Farm, Hothersall Report Ref BEK-17203-1 RevB November 2018
3.1.5 ‘More Vulnerable’ developments within Flood Zone 1 are considered appropriate development. As such it is not considered that the undertaking of a Sequential/Exception Test will be required.
3.2 Historical Flooding 3.2.1 An internet search of flooding in the Hothersall area did not result in any results
however it is acknowledged that the area is essentially rural therefore historical incidents of flooding may not have been recorded.
3.2.2 A review of Ribble Valley Borough Council Strategic Flood Risk Assessment
indicates that there have been a number of historical flood event in the Ribble Valley area however Hothersall or Longridge are not referenced as having flooded.
3.2.3 A number of flooding incidents have been recorded in Ribchester located some
3.8 km south-east of the site however due to the distances involved it is not considered that the site has experienced flooding.
3.3 Surface Water Runoff 3.3.1 The proposed development site is over 1 Hectare in size therefore surface water
runoff will need to be adequately assessed in order to ensure flood risk at the site and elsewhere is not increased as a result of development.
3.3.2 Surface water runoff will be assessed in more detailed in Section 4 of this report. 3.4 Fluvial Flooding 3.4.1 As mentioned previously within Section 2.4 of this report the site is located within
Flood Zone 1 of the Environment Agency flood map. 3.4.2 Flood Zone 1 is defined as land with a low probability (less than 1 in 1000 year
(<0.1% AEP) annual probability of river or sea flooding in any year. 3.4.3 As such the risk to the site from fluvial flooding is considered to be low. 3.5 Reservoir Flooding 3.5.1 The Environment Agency Flooding from Reservoirs map identifies that the
proposed development is within the extent of flooding following a breach of a reservoir.
Flood Risk & Drainage Impact Assessment – Higher College Farm, Hothersall Report Ref BEK-17203-1 RevB November 2018
Figure 6: EA Flood Risk From Reservoir
3.5.2 There are two reservoirs located in close proximity to the site located some 45 m
north of the site at the closest point. The reservoirs are known as Spade Mill Reservoir No 1 and No 2 and are owned by United Utilities.
3.5.3 It is noted that reservoir flooding is extremely unlikely to happen. There has been
no loss of life in the UK from reservoir flooding since 1925. All large reservoirs are regularly inspected by reservoir panel engineers and the EA ensures that reservoirs are regularly inspected and essential safety work is undertaken as appropriate. As such the risk of flooding from this source is considered to be low.
3.6 Groundwater 3.6.1 As mentioned in Section 2.5 of this report the site is underlain by superficial
deposits comprising Boulder Clay and bedrock deposits of the Warley Wise Grit Member.
3.6.2 The superficial deposits are classified by the Environment Agency as a ‘Secondary
Undifferentiated Aquifer’. 3.6.3 The bedrock aquifer designation is classified as a ’Secondary A Aquifer’. 3.6.4 Due to the location of the site on an undifferentiated secondary superficial
aquifer with a bedrock designation as a Secondary A aquifer it is not considered likely that groundwater flooding would pose a significant risk to the proposed site. Furthermore the Ribble Valley Strategic Flood Risk Assessment states that:
‘Groundwater flooding is not considered by the Environment Agency to be a
significant flood risk factor in the Ribble Valley Borough Council area.’
Site
Flood Risk & Drainage Impact Assessment – Higher College Farm, Hothersall Report Ref BEK-17203-1 RevB November 2018
3.6.5 As such the risk to the site from groundwater flooding is considered to be low. 3.7 Surface Water 3.7.1 As mentioned in Section 2.5 of this report the risk of surface water flooding to
the site is considered to be very low to low with a surface water flow route located to the west of the site. As such the risk to the proposed development is considered to be low.
Flood Risk & Drainage Impact Assessment – Higher College Farm, Hothersall Report Ref BEK-17203-1 RevB November 2018
4. INDICATIVE DRAINAGE STRATEGY 4.1 Surface Water Drainage Hierarchy 4.1.1 The hierarchy for disposal of surface water from new developments is outlined
within the Building Regulations Approved Document H and specifies the following methods in order of preference:
Infiltration via soakaway or other suitable infiltration device
Discharge to watercourse
Discharge to public sewer
4.2 Infiltration 4.2.1 Soilscapes viewer maps show that the site is situated on slowly permeable
seasonally wet clayey and loamy soils. These types of soils would generally be unsuitable dissipation of surface water via infiltration.
4.2.2 Although considered very unlikely to be viable, the Lead Local Flood Authority
may request additional evidence that the infiltration is unviable at the site. This can be provided by completing a percolation test in accordance with DG 365 (2016) as part of a detailed drainage design.
4.3 Discharge to Watercourse 4.3.1 The nearest watercourse to the site is a land drain which flows along the western
boundary of the site in a southerly direction, it is understood that the land drain is culverted along the west of the site. The watercourse eventually discharges into the River Ribble some 3.7 km south of the site.
4.3.2 It is proposed that surface water is discharged into this land drain at existing
greenfield runoff rates. 4.4 Preliminary Drainage Design 4.4.1 The purpose of this assessment is to demonstrate that a surface water drainage
strategy is feasible for the development proposals and land available. 4.4.2 The existing site is comprised of a large agricultural field. Therefore flows leaving
the development site will be restricted to existing greenfield runoff rates using a flow control; and excess flows must be attenuated within the new drainage system prior to discharge into the land drain/culverted watercourse which runs adjacent to the west of the site.
4.4.3 It is proposed that foul from the residential dwellings buildings will be pumped
to a receiving foul sewer located towards the north of the site. The foul sewer
Flood Risk & Drainage Impact Assessment – Higher College Farm, Hothersall Report Ref BEK-17203-1 RevB November 2018
has been constructed as part of a new residential development off Dilworth Lane to the north of the site.
4.4.4 A preliminary drainage strategy is included within Appendix D of this report. 4.5 Outfall Locations 4.5.1 The hierarchy of surface water disposal states that surface water should be
discharged into watercourse as discharge via infiltration is unlikely to be viable. The nearest watercourse is a land drain which flows towards the south located to the south-west of the development site.
4.5.2 As such the outfall from the site will be located to the west or south-west into
the existing land drain which eventually discharges into the River Ribble some 3.7 km south of the site.
4.6 Discharge Rates 4.6.1 The existing site is wholly comprised of an agricultural greenfield. 4.6.2 Greenfield runoff rate limits are required to meet normal Greenfield runoff rate
limits are required to meet normal best criteria in line with the Environment Agency Guidance “Preliminary rainfall runoff management for developments”, W5-074/A/TR1/1 Rev. E (2012) and the CIRIA SUDS Manual (2007).
4.6.3 Utilising the HR Wallingford Greenfield Runoff Estimation for Sites website
greenfield runoff rates have been calculated for the 1 in 1 year, 1 in 30 year and 1 in 100 year return periods, and a summary of the results is tabulated below.
4.6.4 Flows in excess of this must be attenuated within the boundary of the
development prior to disposal.
Return Period Qbar Peak Flow Rate Site
1 in 1 year
10.1
8.79
1 in 30 year 17.17
1 in 100 year 21.01
Table 2: Existing Surface Water Runoff (1.13 Hectares) 4.7 On-site Storage Requirements 4.7.1 The proposed development site is comprised of 21 new residential dwellings and
associated hardstanding comprising a total impermeable area of 0.56 Hectares which represents 49.6% of the total site area.
4.7.2 Using the Surface Water Storage Requirement module on HR Wallingford
website indicative attenuation volumes for the 1 in 100 year event has been
Flood Risk & Drainage Impact Assessment – Higher College Farm, Hothersall Report Ref BEK-17203-1 RevB November 2018
calculated below. An additional 20% and 40% has been added to account for climate change over the lifetime of the development.
Return Period Indicative Attenuation Volumes (m3)
No Climate Change 20% Climate
Change 40% Climate
Change
1 in 100 year 201 290 378
Table 3: Indicative Attenuation Volumes (0.56 Hectares Impermeable) 4.7.3 The figures calculated above are indicative at this stage of the project and are
subject to change following the results of percolation testing at the development site, and must not be used for detailed design purposes.
4.7.4 As such it is considered that a geocellular storage tank of 24 m x 11 m and a depth
of 1.6 m at 95% porosity would be sufficient to attenuate flows on site for the 1 in 100 year plus 40% climate change rainfall event prior to discharge at greenfield runoff rate.
4.7.5 Alternatively, a mixture of attenuation and SUDS structures such as oversized
pipes, swales, permeable paving and attenuation storage tanks could be utilised within the site to attenuate surface water prior to discharge.
4.7.6 It is noted that the current proposed site plans indicate that geocellular storage
tanks could be located within the public open space of the site, alternatively private driveways could potentially be constructed from permeable paving, oversized pipes could be utilised beneath the roads within the site and swales could be utilised within the grassed areas of the site.
Flood Risk & Drainage Impact Assessment – Higher College Farm, Hothersall Report Ref BEK-17203-1 RevB November 2018
5. CONCLUSION AND RECOMMENDATIONS
5.1 The proposed development at Higher College Farm, Hothersall comprises the development of 21 residential dwellings and associated infrastructure and landscaping.
5.2 The site is shown to be located within Flood Zone 1 of the Environment Agency
Flood map. 5.3 The primary source of flood risk to the site is identified to be from an increase in
surface water runoff as a result of development. 5.4 Environment Agency surface water flood maps indicate the site is at very low risk
of surface water flooding with a surface water flow route adjacent to the west of the site. It is considered that the surface water flow route is an existing unnamed watercourse/land drain and the risk of flooding from this source to the development is considered to be low.
5.5 The site is within an area that would experience flooding following a breach of
the reservoirs located to the north of the site, however reservoir flooding is extremely unlikely to happen and the EA undertake routine inspection of reservoirs to ensure the risks of failure are low. As such this is considered to represent a low risk of flooding to the site.
5.5 The risks from secondary sources of flooding such as groundwater flooding, river
flooding and artificial water sources have been investigated and are deemed to present a low risk of flooding to the site.
5.6 The site is comprised of an agricultural greenfield therefore greenfield runoff
rates have been determined using IOH124 method. 5.7 Greenfield runoff rates have been determined to be 8.79 l/s, 17.17 l/s and 21.01
l/s for the 1 in 1 year, 1 in 30 year and 1 in 100 year return periods respectively. 5.8 It is considered that infiltration at the site is unlikely to be viable due to the
underlying boulder clay at the site therefore following the hierarchy of surface water disposal, it is recommended that surface water is discharged into the unnamed watercourse/land drain to the west of the site.
5.9 Surface water attenuation requirements have been determined using the limiting
greenfield discharge rate for the site. The maximum attenuation storage required is 378 m3 however this is subject to change following production of a detailed drainage design for the site.
5.10 Therefore the proposed development would be able to manage surface water
generated as a result of the development and would not increase flood risk at the development site or downstream of the site.
APPENDIX A
Topographical Survey
1
0
9
.1
3
1
0
9
.2
6
1
0
8
.9
0
1
0
8
.8
7
1
0
8
.6
9
1
0
8
.6
7
1
0
8
.
5
1
1
0
8
.
5
5
1
0
8
.
3
8
1
0
8
.3
6
1
0
8
.
0
8
1
0
8
.
2
1
1
0
8
.
1
3
1
0
7
.
9
6
1
0
8
.
1
5
1
0
8
.
2
8
1
0
8
.
3
6
1
0
8
.
3
7
1
0
8
.
0
8
1
0
7
.
9
6
1
0
7
.
8
4
1
0
8
.
3
8
1
0
8
.
2
2
1
0
8
.
1
8
1
0
8
.
3
2
1
0
8
.
4
8
1
0
8
.6
8
1
0
8
.
6
9
1
0
8
.
4
4
1
0
8
.
2
9
1
0
8
.
2
2
TARMAC
1
0
8
.
3
5
1
0
8
.
3
5
C
H
1
1
2
.
9
0
C
H
1
1
1
.
7
5
C
H
1
1
5
.
7
0
EH
113.6
3
RH
116.1
4
1
0
8
.
3
9
1
0
8
.
6
3
1
0
8
.
8
1
1
0
8
.
5
6
1
0
8
.
7
1
1
0
8
.
7
4
1
0
8
.
3
0
TP
1
0
7
.
8
9
107.20
107.30
SVP
107.37
1
0
7
.
4
8
1
0
7
.5
8
TARMAC
1
0
7
.
5
4
1
0
7
.
9
8
1
0
8
.
2
3
1
0
7
.
4
0
FFL107.45
CONCRETE
CONCRETE
FFL107.38
107.32
107.27
107.2
1
CONCRETE
WV
CL107.36
107.28
107.46
1
0
8
.
3
3
1
0
7
.
9
2
SVP
R
H
1
1
0
.
0
9
RH
111.11
RH
113.65
RH
112.40
RH
111.71
EH
111.02
EH
110.40
EH
111.03
EH
111.05
EH
109.59
T
W
1
0
8
.
9
5
T
W
1
0
9
.
1
2
107.35
107.4
2
107.4
0
106.7
4
106.72
106.70
EH
109.59
106.8
6
107.20
106.6
0
106.7
1
TW
107.89
TW
107.8
7
TW
108.8
4
106.61
107.01
107.22
107.0
6
107.1
6
107.2
2
107.45
107.3
3
106.80
106.96
107.13
107.41
107.39
106.7
2
107.27
STONE SETTS
STONE SETTS
ST
ON
E F
LA
GS
TL107.4
1
107.2
9
107.4
5
1
0
7
.
4
5
1
0
7
.3
9
107.4
8
CL107.51
S
T
O
N
E
F
L
A
G
S
107.45
107.51
107.33
107.3
1
107.3
0
107.42
107.4
6
1
0
7
.
4
3
107.48
107.42
107.45
107.4
2
CL107.40
TL107.5
3
BOL
BOL
108.08
1
0
8
.0
0
1
0
7
.
9
9
1
0
7
.7
9
1
0
7
.
6
9
WOOD CHIPPINGS
STONE FLAGS
107.94
1
0
7
.9
8
10
7.4
4
107.2
8
107.2
7
107.1
7
107.12
107.29
107.56
107.66
FFL107.56
EH
113.09
EH
110.4
0
EH
113.6
3
RH
112.1
1
TF
109.31
TF
109.09
EH
111.03
EH
110.39
107.49
107.47
107.50
107.48
107.49
107.65
107.70
107.91
107.94
108.18
108.19
CL108.09
108.1
2
108.17
108.2
1
108.2
1
108.641
0
8
.
3
3
TL
10
8.3
1
108.12
10
8.1
0
107.98
10
8.1
5
10
8.1
1
RH110.86
EH110.64
108.42
108.08
108.11
108.14
108.10
CL108.05
108.0
8
TL108.2
7
1
0
8
.
1
0
108.12
TL108.26
TL108.11
CL108.05
108.08
CL108.06
CL108.07
1
0
8
.
0
8
STONE FLAGS
107.64
1
0
7
.
6
4
1
0
7
.
6
9
1
0
7
.
9
7
1
0
8
.
0
8
1
0
7
.
6
2
1
0
7
.
5
3
1
0
7
.9
4
108.09
108.0
8
107.9
5
1
0
7
.
5
2
107.5
3
CL107.40
107.4
5
TL107.5
1
107.5
2
CL107.44
CL107.44
CL107.43
107.5
4
107.5
4
107.37
CH
IPP
ING
S
W
OO
D C
HIP
PIN
GS
107.5
1
107.4
8
107.4
6
CL107.41
STONE FLAGS
STONE FLAGS
GRASS
1
0
8
.3
9
1
0
8
.
3
7
1
0
8
.
4
1
1
0
8
.
8
4
108.6
0
108.5
9
108.4
8
108.6
4
1
0
8
.7
4
108.4
1
108.2
1
108.1
8
108.4
3
108.1
6
108.1
6
108.1
3
EH
110.4
2
108.43
108.45
108.57
CHIPPINGS
1
0
7
.
9
8
108.02
107.80
107.81
1
0
8
.
6
6
108.80
108.50
108.53
1
0
8
.5
5
1
0
8
.6
3
108.62
1
0
8
.6
4
109.2
5
109.1
9
109.0
4
1
0
8
.
5
6
1
0
8
.5
0
1
0
8
.4
5
108.65
1
0
8
.7
3
1
0
9
.
0
1
109.15
1
0
9
.
2
4
1
0
9
.3
7
1
0
9
.
2
6
1
0
9
.
0
4
R
H
115.23
1
0
8
.7
7
108.89
1
0
9
.0
7
1
0
9
.1
5
1
0
9
.2
9
1
0
9
.4
3
1
0
9
.3
4
1
0
9
.3
1
1
0
9
.
2
2
1
0
8
.
8
5
1
0
8
.
3
5
1
0
8
.
2
6
108.1
3
108.2
2
Vent
108.3
2
108.6
7
108.7
9
108.8
1
1
0
8
.5
8
108.34
CL109.42
109.1
6
109.3
5
109.4
5
109.3
7
109.2
7
109.0
0
108.5
8
109.1
0
109.2
9
109.3
6
109.4
5
109.3
7
109.3
8
109.2
3
109.2
0
109.2
8
109.2
2
109.4
0
109.5
3
109.5
8
109.5
5
109.5
7
109.3
7
109.6
4
109.8
5
109.9
4
109.8
9
109.8
6
109.6
2
1
0
8
.8
2
1
0
9
.0
8
1
0
9
.3
7
1
0
9
.0
4
1
0
7
.0
0
m
107.00m
1
0
8
.
0
0
m
1
0
8
.0
0
m
109.00m
1
0
9
.
0
0
m
Hedge
Hedge
Post &
Panel F
ence
H
e
d
g
e
Hedge
H
edge
H
edge
Hedge
P
ost &
W
ire F
ence
Post &
W
ire F
ence
Post &
W
ire F
ence
Post &
W
ire F
ence
Post &
W
ire F
ence
Hedge
H
edge
Hedge
H
e
d
g
e
H
e
d
g
e
H
e
d
g
e
H
e
d
g
e
H
e
d
g
e
CHIPPINGS
CHIPPINGS
CHIPPINGS
Hedge
Hedge
Hedge
H
e
d
g
e
H
e
d
g
e
Reta
inin
g W
all
R
eta
inin
g W
all
R
e
t
a
i
n
i
n
g
W
a
l
l
R
e
t
a
i
n
i
n
g
W
a
l
l
MH
IC
IC
GU
GU
GU
GU
IC
IC
IC
IC
IC
IC
IC
GU
GU
GU
GU
GU
GU
R
e
t
a
i
n
i
n
g
W
a
l
l
GRASS
GRASS
GRASS
GU
MH
MH
GU
Vegetation
Post &
W
ire F
ence
GU
GU
E
H
1
0
9
.
1
9
BBQ
Gully C
hannel
W
a
l
l
W
a
l
l
Wall
W
all
W
all
W
all
GU
MH
GU
MH
GU
108.00m
1
0
8
.0
0
m
Site Address
Project Description
Drawing Title
Scale Date Drawn By
Drawing Number
Rev. Description.
Notes
All Dimensions to be checked on site. Walls shown on
plans are not to be assumed to be solid & should be
checked for thickness, construction, load bearing capacity
& stability.
The contents of this drawing and entities used are copyright TriCAD Solutions Ltd 2010 ©
Higher College Farm
Lower Road
Hothersall PR3 2YY
Site Survey
Existing Site Layout
1:200@A1 30/05/2017 MW
TRI-2005-01
0 Issued
North
0 2 4 6 8 10 12 14 16 18 20Metres
Top of WallTW
Man Hole
Telegraph Pole
Gully
Cover Level
MH
TP
GU
CL
Ridge/Roof HeightRH
Eaves HeightEH
Finished Floor LevelFFL
BT CoverBT
Water ValveWV
Sign PostSP
Soil Vent PipeSVP
Inspection CoverIC
Threshold LevelTL
Cable HeightCH
NOTE
All levels and coordinates relate to OSGB36(15) using GNSS data.
Levels defining edge of carriageway are observed at channel (bottom
of kerb).
Top of FenceTF
BollardBOL
Top of HedgeTH
ABBREVIATIONS
Drop KerbDK
1
23
109.46
109.91
1
1
0
.1
8
110.53
110.86
110.86
111.20
1
1
1
.1
7
1
1
1
.4
4
111.62
1
1
1
.8
7
112.11
112.23
112.19
112.25
1
1
2
.0
7
112.03
109.8
6
109.6
2
109.6
3
109.5
2
109.9
6
109.8
6
109.8
6
110.0
7
110.1
2
110.4
4
110.3
4
110.1
9
110.1
2
110.4
1
110.7
6
110.5
1
110.4
4
110.5
4
110.5
7
110.8
0
110.7
1
110.6
6
111.0
3
111.3
7
110.9
7
110.9
7
110.9
7
111.0
0
111.1
8
111.2
0
111.2
5
111.5
2
111.8
5
111.9
4
111.8
6
111.6
5
T
H
1
1
3
.7
7
T
H
1
1
3
.9
2
TH
113.96
112.68
112.66
112.65
112.59
112.56
112.51
112.50
112.47
112.45
112.38
112.31
1
1
2
.2
8
1
1
2
.2
6
1
1
2
.1
9
1
1
2
.1
5
112.08
112.14
112.25
112.37
112.27
112.33
112.43
112.4
7
112.4
3
1
1
2
.
4
6
1
1
2
.
3
7
1
1
2
.
4
61
1
2
.
5
7
112.46
112.53
112.54
112.49
112.54
112.53
112.56
112.63
112.70
112.63
112.63
112.70
112.75
112.67
112.6
1
TH
114.7
4
112.6
3
112.5
8
112.5
9
112.6
0
112.5
8
TH
114.4
7
1
1
2
.5
9
T
H
1
1
4
.6
9
TH
114.23
112.52
112.48
112.40
1
1
2
.3
6
1
1
2
.1
2
1
1
0
.0
0
m
1
1
1
.
0
0
m
1
1
2
.0
0
m
Post &
W
ire F
ence
Post &
W
ire F
ence
Post &
W
ire F
ence
Post &
W
ire F
ence
Hedge
Hedge
Hedge
GU
GU
GU
GU
H
edge
H
e
d
g
e
K
e
rb
K
erb
K
erb
K
erb
K
erb
K
erb
K
erb
K
erb
K
erb
K
erb
K
erb
DK
361550.626
437261.929
TC
E
N
Ht
04
361676.688
437280.247
112.765
L
o
w
e
r R
o
a
d
Site Address
Project Description
Drawing Title
Scale Date Drawn By
Drawing Number
Rev. Description.
Notes
All Dimensions to be checked on site. Walls shown on
plans are not to be assumed to be solid & should be
checked for thickness, construction, load bearing capacity
& stability.
The contents of this drawing and entities used are copyright TriCAD Solutions Ltd 2010 ©
Higher College Farm
Lower Road
Hothersall PR3 2YY
Site Survey
Existing Site Layout
1:200@A1 30/05/2017 MW
TRI-2005-02
0 Issued
North
0 2 4 6 8 10 12 14 16 18 20Metres
Top of WallTW
Man Hole
Telegraph Pole
Gully
Cover Level
MH
TP
GU
CL
Ridge/Roof HeightRH
Eaves HeightEH
Finished Floor LevelFFL
BT CoverBT
Water ValveWV
Sign PostSP
Soil Vent PipeSVP
Inspection CoverIC
Threshold LevelTL
Cable HeightCH
NOTE
All levels and coordinates relate to OSGB36(15) using GNSS data.
Levels defining edge of carriageway are observed at channel (bottom
of kerb).
Top of FenceTF
BollardBOL
Top of HedgeTH
ABBREVIATIONS
Drop KerbDK
1
23
1
0
9
.8
8
1
0
9
.8
9
1
0
9
.7
4
1
0
9
.7
2
1
0
9
.5
9
1
0
9
.5
0
1
0
9
.1
3
1
0
9
.2
6
1
0
8
.9
0
1
0
8
.8
7
TP
C
H
1
1
7
.
1
6
1
1
2
.0
3
1
1
1
.6
6
111.8
8
112.2
2
112.06
1
1
1
.
9
3
1
1
1
.
7
0
1
1
1
.
2
3
1
1
1
.
0
5
1
1
1
.
2
1
1
1
0
.
8
6
1
1
0
.2
9
109.87
1
0
9
.
8
9
1
0
9
.
4
3
1
0
9
.4
3
1
0
9
.3
4
1
0
9
.3
1
109.5
5
109.6
4
109.8
5
109.9
4
110.1
2
110.1
4
110.0
2
109.5
8
109.9
8
110.2
6
110.3
7
110.4
4
110.5
7
110.5
1
110.2
2
110.0
0
110.7
1
110.6
0
110.7
2
110.8
1
111.0
0
110.9
9
110.9
9
111.3
5
111.5
6
111.8
3
111.3
2
111.2
4
111.1
8
111.5
0
111.5
5
111.8
6
112.0
3
111.6
5
T
H
1
1
3
.
5
0
T
H
113.62
TH
113.5
5
T
H
1
1
3
.7
7
1
0
8
.8
2
1
0
9
.0
8
1
0
9
.3
7
1
0
9
.0
4
1
0
9
.
9
1
1
0
9
.
9
7
1
0
9
.5
2
1
0
9
.9
0
1
1
0
.0
2
1
0
9
.9
2
1
0
9
.9
5
1
1
0
.0
4
1
0
9
.
9
7
1
1
0
.
0
5
1
1
0
.
1
2
1
0
9
.6
7
1
0
9
.8
1
1
0
9
.8
8
1
0
9
.9
9
1
1
0
.0
0
1
1
0
.
4
0
1
1
0
.
0
9
1
1
0
.
1
9
1
1
0
.
4
8
1
1
0
.
3
8
1
1
0
.
3
0
1
1
0
.
4
0
1
1
0
.
6
7
1
1
1
.
1
6
1
1
0
.
8
5
C
H
118.48
1
1
2
.1
9
1
1
2
.0
9
1
1
1
.9
6
1
1
1
.8
1
1
1
1
.5
7
1
1
1
.3
6
1
1
1
.2
3
1
1
1
.1
3
111.02
1
1
1
.
1
0
1
1
1
.1
8
1
1
1
.1
3
1
1
1
.2
9
111.58
111.8
5
112.0
3
112.1
2
111.93
111.82
1
1
1
.5
7
111.66
1
1
1
.3
8
1
1
1
.3
1
1
1
1
.1
3
1
1
1
.2
0
1
1
1
.1
1
1
1
1
.0
5
1
1
0
.9
7
1
1
1
.0
3
1
1
1
.1
1
1
1
1
.0
7
1
1
1
.
1
1
BOL
BOL
CL110.98
TARMAC
CHIPPINGS
1
1
0
.
8
1
1
1
0
.
4
4
1
1
0
.
2
9
1
1
0
.
2
3
1
1
0
.
3
0
1
1
0
.
5
4
1
1
1
.
1
3
111.4
5
1
1
1
.1
8
1
1
1
.
3
4
P
o
s
t
&
R
a
il
F
e
n
c
e
1
1
2
.1
3
P
o
s
t &
W
ire
F
e
n
c
e
112.0
0
1
1
1
.9
4
1
1
2
.1
5
1
1
2
.2
7
112.45
SP
TP
BT
T
H
1
1
2
.
7
4
T
H
1
1
2
.8
2
T
H
1
1
3
.7
0
SP
111.18
1
1
1
.
1
5
1
1
1
.2
6
1
1
1
.3
3
1
1
1
.5
5
1
1
1
.4
9
1
1
1
.6
7
1
1
1
.7
7
1
1
1
.9
0
1
1
1
.8
4
1
1
1
.9
5
1
1
2
.0
2
1
1
2
.1
5
112.08
1
1
1
.9
3
112.03
112.2
1
111.8
6
111.68
111.80
1
1
1
.8
1
109.00m
1
1
0
.
0
0
m
111.0
0m
112.00m
1
1
2
.
0
0
m
1
1
2
.0
0
m
GU
112.05
GU
GU
GU
GU
GU
GU
MH
Hedge
H
e
d
g
e
H
e
d
g
e
H
e
d
g
e
H
e
d
g
e
H
e
d
g
e
H
e
d
g
e
H
e
d
g
e
H
e
d
g
e
H
e
d
g
e
H
edge
TH
114.41
T
H
1
1
3
.8
2
Kerb
Kerb
K
e
rb
K
e
rb
K
e
rb
K
e
rb
K
e
rb
K
e
rb
K
e
rb
K
e
rb
K
e
rb
DK
DK
CHIPPINGS
CHIPPINGS
TC
E
N
Ht
01
361443.031
437243.911
111.630
TC
E
N
Ht
02
361492.239
437253.205
111.244
TC
E
N
Ht
03
361550.626
437261.929
112.201
L
o
w
e
r R
o
a
d
Site Address
Project Description
Drawing Title
Scale Date Drawn By
Drawing Number
Rev. Description.
Notes
All Dimensions to be checked on site. Walls shown on
plans are not to be assumed to be solid & should be
checked for thickness, construction, load bearing capacity
& stability.
The contents of this drawing and entities used are copyright TriCAD Solutions Ltd 2010 ©
Higher College Farm
Lower Road
Hothersall PR3 2YY
Site Survey
Existing Site Layout
1:200@A1 30/05/2017 MW
TRI-2005-03
0 Issued
North
0 2 4 6 8 10 12 14 16 18 20Metres
Top of WallTW
Man Hole
Telegraph Pole
Gully
Cover Level
MH
TP
GU
CL
Ridge/Roof HeightRH
Eaves HeightEH
Finished Floor LevelFFL
BT CoverBT
Water ValveWV
Sign PostSP
Soil Vent PipeSVP
Inspection CoverIC
Threshold LevelTL
Cable HeightCH
NOTE
All levels and coordinates relate to OSGB36(15) using GNSS data.
Levels defining edge of carriageway are observed at channel (bottom
of kerb).
Top of FenceTF
BollardBOL
Top of HedgeTH
ABBREVIATIONS
Drop KerbDK
1
23
APPENDIX B
Greenfield Runoff Rates
This report was produced using the greenfield runoff tool developed by HR Wallingford and available at www.uksuds.com. The use of this tool is subject to the UK SuDS terms and conditions and licence agreement, which can both be found at http://uksuds.com/terms-and-conditions.htm. The outputs from this tool have been used to estimate storage volume requirements. The use of these results is the responsibility of the users of this tool. No liability will be accepted by HR Wallingford, the Environment Agency, CEH, Hydrosolutions or any other organisation for use of this data in the design or operational characteristics of any drainage scheme.
Greenfield runoff estimation for sites
www.uksuds.com │ Greenfield runoff tool
This is an estimation of the greenfield runoff rate limits that are needed to meet normal best practice criteria in line with Environment Agency guidance “Preliminary rainfall runoff management for developments”, W5-074/A/TR1/1 rev. E (2012) and the SuDS Manual, C753 (Ciria, 2015). This information on greenfield runoff rates may be the basis for setting consents for the drainage of surface water runoff from sites.
Site name:
Calculated by:
Latitude:
Longitude:
Reference:
Date:
Site coordinates
Site location:
Site characteristicsTotal site area (ha)
MethodologyQbar estimation methodSPR estimation method
Default Edited
SOIL typeHOST classSPR/SPRHOST
Hydrological characteristics Default Edited
SAAR (mm)Hydrological region Growth curve factor: 1 year Growth curve factor: 30 year Growth curve factor: 100 year
Notes:(1) Is QBAR < 2.0 l/s/ha?
(2) Are flow rates < 5.0 l/s?
(3) Is SPR/SPRHOST ≤ 0.3?
Greenfield runoff rates Default Edited
Qbar (l/s)1 in 1 year (l/s)1 in 30 years (l/s)1 in 100 years (l/s)
Methodology IH124
0.47
8.79
1.7
21.01
0.87 0.87
10
1.13
2018-11-22T12:42:45
Hothersall
---
2.5854° W
8.79
Higher College Farm
10.1
David Emmott
2.08
10.1
Calculate from SOIL type
53.82953° N
11851185
44
21.01
2.08
Calculate from SPR and SAAR
10
---
17.17 17.17
1.7
6494316
0.47
APPENDIX C
On-site Storage Requirements
Surface water storage requirements for sites
www.uksuds.com │ Storage estimation tool
This report was produced using the Storage estimation tool developed by HR Wallingford and available at www.uksuds.com. The use of this tool is subject to the UK SuDS terms and conditions and licence agreement, which can both be found at http://uksuds.com/terms-and-conditions.htm. The outputs from this tool have been used to estimate storage volume requirements. The use of these results is the responsibility of the users of this tool. No liability will be accepted by HR Wallingford, the Environment Agency, CEH, Hydrosolutions or any other organisation for use of this data in the design or operational characteristics of any drainage scheme.
This is an estimation of the storage volume requirements that are needed to meet normal best practice criteria in line with Environment Agency guidance “Preliminary rainfall runoff management for developments”, W5-074/A/TR1/1 rev. E (2012) and the SuDS Manual, C753 (Ciria, 2015). It is not to be used for detailed design of drainage systems. It is recommended that hydraulic modelling software is used to calculate volume requirements and design details before finalising the drainage scheme.
Site name:
Calculated by:
Latitude:
Longitude:
Reference:
Date:
Site coordinates
Site location:
* Where rainwater harvesting or infiltration has been used for managing surface water runoff such that the effective impermeable area is less than 50 % of the ‘area positively drained’, the ‘net site area’ and the estimates of Qbar and other flow rates will have been reduced accordingly.
Site characteristicsTotal site area (ha)Significant public open space (ha)Area positively drained (ha)Pervious area contribution (%)Impermeable area (ha)Percentage of drained area that is impermeable (%)Impervious area drained via infiltration (ha)Return period for infiltration system design (year)Impervious area drained to rainwater harvesting systems (ha)Return period for rainwater harvesting system design (year)Compliance factor for rainwater harvesting system design (%)Net site area for storage volume design (ha)Net impermeable area for storage volume design (ha)
Design criteriaVolume control approach
Default Edited
Climate change allowance factorUrban creep allowance factorInterception rainfall depth (mm)Minimum flow rate (l/s)
Qbar estimation methodSPR estimation method
Default Edited
Qbar total site area (l/s)SOIL typeHOST classSPR
Hydrology Default Edited
SAAR (mm)M5-60 Rainfall Depth (mm)‘r’ Ratio M5-60/M5-2 day Rainfall 100 yrs 6 hrsRainfall 100 yrs 12 hrsFEH/FSR conversion factor Hydrological region Growth curve factor: 1 year Growth curve factor: 10 yearGrowth curve factor: 30 year Growth curve factor: 100 year
Site discharge rates Default Edited
Qbar total site area (l/s)Qbar net site area (l/s)1 in 1 year (l/s)1 in 30 years (l/s)1 in 100 years (l/s)
Estimated storage volumes Default Edited
Interception storage (m3)Attenuation storage (m3)Long term storage (m3)Treatment storage (m3)Total storage (excluding treatment) (m3)
Methodology IH124
1.0
Use long term storage
Calculate from SOIL type
5
5.01
1.1 1.1
0.47
10.1
91
N/A
30
70
Calculate from SPR and SAAR
0
8.5
David Emmott
5
1.7
1.19
6767
11851185
5
Longridge
1.0
10
91
N/A
22
53.82923° N
0.5599999999999999
1.7
20
0.87 0.87
--
0.3
10.1100
6494322
0.47
2.08
1.38
315
0.57
10.410.4
20
0
1.13
2.58537° W
2018-11-22T12:58:55
8.5
99.96
2.08
10
0.366
315
0.56
0.5599999999999999
22
5.01
0.56
5
10
1.19
1.38
4 4
201201
Higher College
5
5
10.1
Surface water storage requirements for sites
www.uksuds.com │ Storage estimation tool
This report was produced using the Storage estimation tool developed by HR Wallingford and available at www.uksuds.com. The use of this tool is subject to the UK SuDS terms and conditions and licence agreement, which can both be found at http://uksuds.com/terms-and-conditions.htm. The outputs from this tool have been used to estimate storage volume requirements. The use of these results is the responsibility of the users of this tool. No liability will be accepted by HR Wallingford, the Environment Agency, CEH, Hydrosolutions or any other organisation for use of this data in the design or operational characteristics of any drainage scheme.
This is an estimation of the storage volume requirements that are needed to meet normal best practice criteria in line with Environment Agency guidance “Preliminary rainfall runoff management for developments”, W5-074/A/TR1/1 rev. E (2012) and the SuDS Manual, C753 (Ciria, 2015). It is not to be used for detailed design of drainage systems. It is recommended that hydraulic modelling software is used to calculate volume requirements and design details before finalising the drainage scheme.
Site name:
Calculated by:
Latitude:
Longitude:
Reference:
Date:
Site coordinates
Site location:
* Where rainwater harvesting or infiltration has been used for managing surface water runoff such that the effective impermeable area is less than 50 % of the ‘area positively drained’, the ‘net site area’ and the estimates of Qbar and other flow rates will have been reduced accordingly.
Site characteristicsTotal site area (ha)Significant public open space (ha)Area positively drained (ha)Pervious area contribution (%)Impermeable area (ha)Percentage of drained area that is impermeable (%)Impervious area drained via infiltration (ha)Return period for infiltration system design (year)Impervious area drained to rainwater harvesting systems (ha)Return period for rainwater harvesting system design (year)Compliance factor for rainwater harvesting system design (%)Net site area for storage volume design (ha)Net impermeable area for storage volume design (ha)
Design criteriaVolume control approach
Default Edited
Climate change allowance factorUrban creep allowance factorInterception rainfall depth (mm)Minimum flow rate (l/s)
Qbar estimation methodSPR estimation method
Default Edited
Qbar total site area (l/s)SOIL typeHOST classSPR
Hydrology Default Edited
SAAR (mm)M5-60 Rainfall Depth (mm)‘r’ Ratio M5-60/M5-2 day Rainfall 100 yrs 6 hrsRainfall 100 yrs 12 hrsFEH/FSR conversion factor Hydrological region Growth curve factor: 1 year Growth curve factor: 10 yearGrowth curve factor: 30 year Growth curve factor: 100 year
Site discharge rates Default Edited
Qbar total site area (l/s)Qbar net site area (l/s)1 in 1 year (l/s)1 in 30 years (l/s)1 in 100 years (l/s)
Estimated storage volumes Default Edited
Interception storage (m3)Attenuation storage (m3)Long term storage (m3)Treatment storage (m3)Total storage (excluding treatment) (m3)
Methodology IH124
1.2
Use long term storage
Calculate from SOIL type
5
5.01
1.1 1.1
0.47
10.1
91
N/A
30
70
Calculate from SPR and SAAR
0
8.5
David Emmott
5
1.7
1.19
6767
11851185
5
Longridge
1.2
10
91
N/A
22
53.82923° N
0.5599999999999999
1.7
20
0.87 0.87
--
0.3
10.1100
6494322
0.47
2.08
1.38
404
0.57
10.410.4
20
0
1.13
2.58537° W
2018-11-22T12:58:20
8.5
99.96
2.08
10
0.366
404
0.56
0.5599999999999999
22
5.01
0.56
5
10
1.19
1.38
4 4
290290
Higher College
5
5
10.1
Surface water storage requirements for sites
www.uksuds.com │ Storage estimation tool
This report was produced using the Storage estimation tool developed by HR Wallingford and available at www.uksuds.com. The use of this tool is subject to the UK SuDS terms and conditions and licence agreement, which can both be found at http://uksuds.com/terms-and-conditions.htm. The outputs from this tool have been used to estimate storage volume requirements. The use of these results is the responsibility of the users of this tool. No liability will be accepted by HR Wallingford, the Environment Agency, CEH, Hydrosolutions or any other organisation for use of this data in the design or operational characteristics of any drainage scheme.
This is an estimation of the storage volume requirements that are needed to meet normal best practice criteria in line with Environment Agency guidance “Preliminary rainfall runoff management for developments”, W5-074/A/TR1/1 rev. E (2012) and the SuDS Manual, C753 (Ciria, 2015). It is not to be used for detailed design of drainage systems. It is recommended that hydraulic modelling software is used to calculate volume requirements and design details before finalising the drainage scheme.
Site name:
Calculated by:
Latitude:
Longitude:
Reference:
Date:
Site coordinates
Site location:
* Where rainwater harvesting or infiltration has been used for managing surface water runoff such that the effective impermeable area is less than 50 % of the ‘area positively drained’, the ‘net site area’ and the estimates of Qbar and other flow rates will have been reduced accordingly.
Site characteristicsTotal site area (ha)Significant public open space (ha)Area positively drained (ha)Pervious area contribution (%)Impermeable area (ha)Percentage of drained area that is impermeable (%)Impervious area drained via infiltration (ha)Return period for infiltration system design (year)Impervious area drained to rainwater harvesting systems (ha)Return period for rainwater harvesting system design (year)Compliance factor for rainwater harvesting system design (%)Net site area for storage volume design (ha)Net impermeable area for storage volume design (ha)
Design criteriaVolume control approach
Default Edited
Climate change allowance factorUrban creep allowance factorInterception rainfall depth (mm)Minimum flow rate (l/s)
Qbar estimation methodSPR estimation method
Default Edited
Qbar total site area (l/s)SOIL typeHOST classSPR
Hydrology Default Edited
SAAR (mm)M5-60 Rainfall Depth (mm)‘r’ Ratio M5-60/M5-2 day Rainfall 100 yrs 6 hrsRainfall 100 yrs 12 hrsFEH/FSR conversion factor Hydrological region Growth curve factor: 1 year Growth curve factor: 10 yearGrowth curve factor: 30 year Growth curve factor: 100 year
Site discharge rates Default Edited
Qbar total site area (l/s)Qbar net site area (l/s)1 in 1 year (l/s)1 in 30 years (l/s)1 in 100 years (l/s)
Estimated storage volumes Default Edited
Interception storage (m3)Attenuation storage (m3)Long term storage (m3)Treatment storage (m3)Total storage (excluding treatment) (m3)
Methodology IH124
1.4
Use long term storage
Calculate from SOIL type
5
5.01
1.1 1.1
0.47
10.1
91
N/A
30
70
Calculate from SPR and SAAR
0
8.5
David Emmott
5
1.7
1.19
6767
11851185
5
Longridge
1.4
10
91
N/A
22
53.82923° N
0.5599999999999999
1.7
20
0.87 0.87
--
0.3
10.1100
6494322
0.47
2.08
1.38
492
0.57
10.410.4
20
0
1.13
2.58537° W
2018-11-22T12:54:58
8.5
99.96
2.08
10
0.366
492
0.56
0.5599999999999999
22
5.01
0.56
5
10
1.19
1.38
4 4
378378
Higher College
5
5
10.1
APPENDIX D
Preliminary Drainage Design
G
eocellula
r S
torage
24 m
x 11 m
x1.6 m
Foul connection into
existing foul sewer north
of site. Exact location to
be confirmed
Surface Water Connection
into watercourse restricted
to greenfield runoff rates
Hydrobrake or similar to
restrict discharge rate
from geocelluar tank
LEGEND
FILE_NAME
HIGHER COLLEGEFARMHOUSE, HOTHERSALL,
PRESTON
NTS D.E. M.B. 23/11/18
17303-5 -
PRELIMINARY DRAINAGEDESIGN
Suite One, No 3 Mitton Road Business Park, Mitton Road,Whalley, Lancashire BB7 9YE
Tel: 01254 377622 Mob: 07906753583 Email: [email protected]
Web: www.bekenviro.co.uk
PROPOSED SURFACE
WATER DRAIN
MR M HURST
PROPOSED SW
MANHOLE
PROPOSED FOUL
DRAIN
PROPOSED FOUL
MANHOLE